The present invention generally relates to method and apparatus for preventing barnacles and other marine life from attaching to the hull of a boat.
The problem of barnacles attaching themselves to the hull of a boat has plagued man for centuries. One solution to this problem is of course to remove the boat from the water after each use; however this is very expensive and impractical and besides barnacles, though to a much lesser degree, can also grow on an object moving in the water.
Special paints for the hulls of boats have been developed to prevent barnacles and other marine life from attaching to the hull, these paints function by poisoning the life forms that come in contact with them. In general these paints are referred to as anti-fouling paints and the most popular and effective anti-fouling paint is one containing tin in the form of tributyl-tin, or T.B.T. as it is more widely known. Apparently anti-fouling paint functions by leaching toxic chemicals into the water surrounding a boat thus repelling the growth of barnacles as well as other forms of marine life. However the use of this paint obviously creates an environmental hazard affecting fish-life and in turn fish food and humans due to the toxicity of tin. Several states have now banned the use of T.B.T. as an anti-fouling agent and other countries of the world have joined in a similar ban.
After the aforementioned ban industry reverted to an anti-fouling paint containing copper which itself is a toxin. This paint had been used before the advent of T.B.T. but did not function as well. Since this paint has a relatively short effective life and since it is also toxic to a certain degree, it is not believed to be wholly satisfactory for preventing barnacle growth.
Research has been carried out over many years on the effectiveness of vibrations in controlling the problem of marine fouling on the hulls of boats. One such example is that carried out by P. V. Murphy and M. Latour of Lectret S. A. of Switzerland, and the University of Science and Technology of Languedoc, France. They reported the conclusions of their revised tests in October 1980 as follows: "High frequency vibrations of low level discourage the attachment of most fouling species. Both vegetable and animal species are affected. Additional work is required to quantify the minimum vibration levels and maximum periods of protection. Piezo-electric plastic films are effective vibration exciters especially for laminated ship hulls".
More recently research carried out by E. Sanford Branscomb and Dan Rittschaf at Duke University Marine Laboratory, North Carolina in 1983/84 found that low frequency sound waves aid in the prevention of barnacles from attaching to the hulls of boats.
The present invention is directed to the use of low frequency vibrations for preventing or inhibiting the growth of barnacles and other marine life on the hulls of boats or similar vessels.